This invention relates generally to methods and apparatuses for the analysis of vessel images, and more particularly to methods and apparatus for assisting medical care personnel such as radiologists in preparing measurements and reports for surgical planning from images derived from computed tomographic, MR, and 3D radiation imaging.
In at least some computed tomography (CT) imaging system configurations, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the xe2x80x9cimaging planexe2x80x9d. The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal spot. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector, a scintillator adjacent the collimator, and photodetectors adjacent the scintillator.
An important application of computed tomographic (CT) imaging systems, as well as magnetic resonance (MR) imaging and 3-D x-ray (XR) imaging systems, is to produce 3D image data sets for vascular analysis, which can include analysis of a variety of tortuous tubular structures such as airways, ducts, nerves, blood vessels, etc. Production of such 3D image data sets is particularly important for radiologists, who are called upon to provide thorough visual reports to allow assessments of stenosis or aneurysm parameters, quantify lengths, section sizes, angles, and related parameters. Information concerning, for example, the most acute stenosis on a selected vessel section, the largest aneurysm on a selected vessel section, or the tortuosity of a vessel, is commonly utilized by physicians to allow for surgical planning. For productivity reasons, as well as to reduce film costs, the 3D image data sets should be limited to only a small set of significant images.
To facilitate the obtaining of useful information for vascular analysis in an efficient manner, conventional medical imaging systems sometimes provide 3D visualization software. Such software is provided either on the imaging systems themselves or on analysis workstations, and provides a set of tools to perform length, angle or volume measurements and to visualize a volume in different ways, for example, using cross-sections, navigator or volume rendering. With respect to vascular analysis, in particular, the software can be used to obtain multiple oblique slices of a particular vessel to allow for analysis of the vessel.
However, use of such conventional software and related tools is highly operator dependent, and requires both time and software expertise. Selecting the best images to depict anatomical features or lesions particularly is a time-consuming and operator-dependent task, since one needs to adjust 5 independent parameters to select a plane and it often is difficult to adjust the view since the objects of interest usually are not entirely visible. For example, a trained operator may need more than one hour to complete a single abdominal aorta aneurysm case. Even with trained operators given all the required time, results are not particularly reproducible and there are no consistent reporting frameworks. Further, some measurements, such as true 3D-length measurement along vessels, cannot be performed using known manual tools. Because of these limitations, only a small number of sites are able to provide high-quality reports.
Therefore, it would be advantageous if new methods and apparatuses were developed for allowing medical imaging systems and related 3D visualization software to produce useful 3D imaging data sets in a more efficient, consistent, repeatable, rapid, and less operator-dependent manner. It would particularly be advantageous if such new methods and apparatuses facilitated vascular analysis, including the analysis and imaging of tubular vessels and related stenoses, aneurysms, and tortuosity. It further would be advantageous if such methods and apparatuses could be employed both during imaging and in post-processing after imaging is completed.
The present invention is a set of methods and apparatuses that automatically determine the best slice plane settings for vascular images in a consistent manner by defining the planes of interest in relation to points along a centerline. By determining the best slice plane settings in this manner, images of stenoses, aneurysms and tortuous features can be consistently and repeatably obtained. These methods and apparatuses can be used to produce images on a post-processing system or to select an orientation and location during operation of an imaging system. Further, all the methods may be used in a xe2x80x9cbatchxe2x80x9d mode where selected points or sections are sampled repeatably at some interval along the centerline of the structure of interest to produce a complete set of images that depict the complete structure.
In particular, the present invention relates to a method of displaying a structure of a vessel. The method includes identifying a centerline of the vessel within at least a portion of the vessel that includes the structure, identifying a contour of the vessel within a cross-sectional plane that is normal to a selected point along the centerline, measuring lengths of a plurality of segments that pass across the contour through the selected point, and selecting one of the plurality of segments. The method further includes at least one of displaying at least a part of an imaging plane defined by the selected one segment and an axis that is tangent to the centerline at the point, where the imaging plane shows the structure of the vessel, and performing an image acquisition in relation to the imaging plane.
The present invention further relates to an apparatus for displaying a portion of a tubular vessel. The apparatus includes means for selecting at least one point along a centerline of the vessel proximate the portion, means for identifying an imaging plane based upon the selected at least one point, and at least one of means for displaying at least a part of the imaging plane, and means for acquiring an image in relation to the imaging plane.
The present invention additionally relates to a method of displaying a structure of a vessel. The method includes determining a centerline of a tubular structure, selecting a section of the centerline, and determining a plane that minimizes the distance to the selected section. The method further includes at least one of displaying at least a part of the plane, and performing an image acquisition in relation to the plane.